Process for manufacturing a nozzle plate and fluid-ejection device provided with the nozzle plate

ABSTRACT

A nozzle plate for a fluid-ejection device, comprising: a first substrate made of semiconductor material, having a first side and a second side; a structural layer extending on the first side of the first substrate, the structural layer having a first side and a second side, the second side of the structural layer facing the first side of the first substrate; at least one first through hole, having an inner surface, extending through the structural layer, the first through hole having an inlet section corresponding to the first side of the structural layer and an outlet section corresponding to the second side of the structural layer; a narrowing element adjacent to the surface of the first through hole, and including a tapered portion such that the inlet section of the first through hole has an area larger than a respective area of the outlet section of the first through hole.

BACKGROUND

1. Technical Field

The present disclosure relates to a process for manufacturing a nozzleplate and a fluid-ejection device comprising said nozzle plate.

2. Description of the Related Art

Devices for ejecting liquids or, in general, fluids in the form of drops(such as for example inhalers, printing heads, etc.) generally comprisea nozzle plate set facing a reservoir containing the liquid to beejected. An actuation element, for example a piezoelectric element, canbe used for deforming the reservoir and causing exit of the liquidthrough the nozzles of the membrane. Another known technology forejecting liquid is thermal technology (known as thermal inkjet or bubbleinkjet), where a heater, set between each nozzle and the reservoir, isconfigured to generate a bubble of vapor that causes ejection of liquidfrom the respective nozzle.

It is clear that, irrespective of the ejection technology used, the sizeand shape of the nozzles, as well as the uniformity of size and shape ofthe nozzles, are particularly important parameters for defining the sizeand directionality of the drops generated and their reproducibility.

Generally, the nozzles have a cylindrical shape with an outlet diametersmaller than the diameter of the channel that supplies the nozzles withthe liquid to be ejected. Frequently, between the supply channel and therespective nozzle, a substantially frustoconical connection element ismoreover provided having a major-base section (with a diameter equal tothe diameter of the supply channel) coupled to the supply channelitself, and a minor-base section (with a diameter equal to the diameterof the base section of the nozzle) coupled to the nozzle. Thisconfiguration enables an increase in the speed of ejection the dropsgenerated. However, the coupling step, in particular between theconnection element and the nozzle, is not easy, and is frequently thecause of undesirable misalignments.

In addition, nozzles having an outlet mouth that protrudes from thenozzle plate are particularly subject to damage, and to the undesirabledeposit of material that is likely to create an obstacle to ejection ofthe liquid. A further disadvantage of said nozzle plates is thedependence of the drop ejected upon the outer structural conformation ofthe nozzles.

BRIEF SUMMARY

One or more embodiments of the present disclosure are directed toproviding a process for manufacturing a nozzle plate for afluid-ejection device, a nozzle plate for a fluid-ejection device, and afluid-ejection device that uses said nozzle plate.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a better understanding of the present disclosure preferredembodiments thereof are now described, purely by way of non-limitingexample, with reference to the attached drawings, wherein:

FIG. 1 a is a sectioned perspective view of a portion of afluid-ejection device provided with a nozzle plate including a nozzle,according to one embodiment of the present disclosure;

FIG. 1 b is a sectioned perspective view of a portion of afluid-ejection device provided with a nozzle plate including a nozzle,according to a further embodiment of the present disclosure;

FIGS. 2-12 show, in lateral sectional view, steps for manufacturing thenozzle plate of FIG. 1 a according to one embodiment of the presentdisclosure;

FIGS. 13-19 show, in lateral sectional view, steps for manufacturing thenozzle plate of FIG. 1 a according to a further embodiment of thepresent disclosure;

FIGS. 20-27 show, in lateral sectional view, steps for manufacturing thenozzle plate of FIG. 1 b according to one embodiment of the presentdisclosure;

FIG. 28 is a lateral sectional view of a fluid-ejection device,comprising a nozzle plate housing a plurality of nozzles; and

FIG. 29 illustrates a printing machine comprising the ejection device ofFIG. 1 a or FIG. 1 b or FIG. 28.

DETAILED DESCRIPTION

FIGS. 1 a and 1 b show, in perspective view, a respective fluid-ejectionelement 1′, 1″ according to respective embodiments of the presentdisclosure. Features that are common to both of the fluid-ejectionelements 1′, 1″ are designated in what follows by the same referencenumbers.

The fluid-ejection elements 1′, 1″ comprise, respectively, a plate 2provided with one or more nozzles 4 (just one nozzle 4 is illustrated inFIGS. 1 a and 1 b). In particular, the views of FIGS. 1 a and 1 b showthe respective fluid-ejection element 1′, 1″ sectioned along a diameterof the nozzle 4, which, in this representation, has a substantiallycircular cross section.

The plate 2 is provided with a first side and a second side, opposite toone another in the direction Z. Set underneath the plate 2, on thesecond side 2 b, is a reservoir 6, provided with an ejection channel 8fluidically coupled to the nozzle 4. The reservoir 6 is configured tocontain a liquid or fluid to be ejected through the nozzle 4. Ejectionis obtained, according to one embodiment, by means of a piezoelectricelement (not illustrated in FIGS. 1 a and 1 b), having the function ofan actuator to enable ejection of the fluid through the nozzle 4. Whenactivated by means of an appropriate control electronics (notillustrated), said piezoelectric actuator induces a vibration that istransmitted to the fluid contained in the ejection channel 8, causingexit thereof through the nozzle 4. Other types of actuators may be used,for example actuators of a thermal type, operating according to “thermalinkjet” technology.

According to the embodiment of FIG. 1 a, the nozzle 4 is made in theform of hole that extends completely through the plate 2, in a region ofthe latter provided with a recess 2′, formed in a position correspondingto the first side 2 a of the plate 2.

The recess 2′ can have any shape, for example a quadrangular, orpolygonal shape (possibly with rounded corners), or else a circular oroval shape. An oval shape or a polygonal shape with rounded cornersfacilitates possible operations of cleaning of the recess 2′. Accordingto one embodiment, the recess 2′ has axial symmetry with respect to thearea in which the nozzle 4 is set.

When the recess 2 has rounded corners, rounding of said corners may beobtained by means of an etching step.

The nozzle 4 forms a passage for the fluid contained in the reservoir 6towards the outside of the fluid-ejection element 1′. An inlet section 4a of the nozzle 4 is fluidically coupled directly to the ejectionchannel 8, whereas an outlet section 4 b of the nozzle 4 extends in anarea corresponding to the recess 2′. The distance D_(N), in thedirection Z, between the inlet section 4 a and the outlet section 4 bcorresponds to the thickness of the plate 2 (distance, along Z, betweenthe first and second sides 2 a, 2 b) minus the depth of the recess 2′.As will be described in greater detail hereinafter, said distancefurther comprises, according to one embodiment of the presentdisclosure, the thickness of a protective layer designated by thereference number 9.

The outlet section 4 b of the nozzle 4 has, in top view (i.e., viewingthe nozzle 4 in the direction Z) a substantially circular shape with adiameter d₁. Also the inlet section 4 a has, in top view, asubstantially circular shape, but with a diameter d₂ larger than thediameter d₁. This configuration of the nozzle 4, where the inlet section4 a is directly coupled to the ejection channel 8 and has a diameter d₂larger than the diameter d₁ of the outlet section 4 b, which extends inan area corresponding to the recess 2′, presents the advantage ofenabling the generation, during use, of drops being ejected and having ahigh exit speed. In particular, the speed of said drops is greater thanthe one that can be obtained by means of nozzles having a substantiallycylindrical shape, where the inlet section 4 a has a diameterapproximately equal to that of the outlet section 4 b. According to oneaspect of the present disclosure, the inlet section 4 a and/or theoutlet section 4 b have rounded corners.

According to one aspect of the present disclosure, the recess 2′ extendsso as to surround the nozzle 4 at least partially. In this case, thenozzle 4 extends at least partially in the recess 2′. According to afurther aspect of the present disclosure, the recess 2′ extends so as tosurround the nozzle 4 completely. In this case, the nozzle 4 extendscompletely in the recess 2′.

The recess 2′ is delimited by walls 3′ set at a distance from the nozzle4 in such a way as to not hinder, or interfere with, ejection of theliquid during use of the fluid-ejection element 1′. For example, thewalls 3′ extend at a minimum distance D_(R), measured starting from theedge of the outlet section 4 b of the nozzle 4 up to interception of theclosest point of the walls 3′, between approximately 3 μm andapproximately 30 μm, in particular between approximately 5 μm andapproximately 20 μm, for example approximately 10 μm. The recess 2′extends in the structural layer 16 for a depth, measured starting fromthe first side 2 a of the structural layer 2, between 0.1 μm and 10 μm,for example 1 μm.

According to one embodiment, the walls 3′ are vertical, and extendparallel to the axis Z. According to a further embodiment, the walls 3′extend in a plane inclined with respect to the axis Z.

Moreover, the angle between the walls 3′ and the surface 2 a of theplate 2, according to one embodiment, is an angle of approximately 90°.In addition, according to one embodiment, the edge defined by the regionwhere the walls 3′ encounter the surface 2 a of the plate 2, is rounded.This is useful when cleaning the plate 2 and the recess 2′, as well ascleaning the walls 3′.

The presence of the recess 2′ prevents any debris, for example derivingfrom the process of ejection of the fluid from the nozzle 4, and/orundesirable material with which the plate 2 might come into contactduring use from possibly interfering with ejection of the fluid from thenozzle 4. In particular, if the plate 2 is set in contact with a dirtysurface, since the outlet section 4 b of the nozzle 4 is formed in therecess 2′, it is not in direct contact with said dirty surface, thusreducing the possibility of obstruction of the nozzle 4.

According to one aspect of the present disclosure, the nozzle plate 2further comprises a protective layer 9 that extends in such a way as tocover the base surface of the recess 2′ and the walls of the hole thatforms the nozzle 4 (i.e., the walls that connect the inlet section 4 awith the outlet section 4 b). The protective layer 9 is made of amaterial that does not undergo a significant degradation when set in(even prolonged) contact with the fluid that is to be ejected throughthe nozzle 4. In this way, even in the case where corrosive fluids areejected, the nozzle does not undergo a degradation such as to jeopardizeeffective use thereof for the application considered. It is evident thatthe choice of the material used for the protective layer 9 depends uponthe type of use envisaged for the fluid-ejection element 1′. Forexample, in the case where the fluid to be ejected is ink, materialsthat can be used for the protective layer 9 are, for example, siliconcarbide, alumina, hafnium oxide, titanium, tantalum, tungsten, and/oralloys thereof.

In general, the protective layer 9 can have also the function ofimproving the resistance in regard to the operations of cleaning of thefluid-ejection element 1′, improving the sturdiness thereof, modifyingthe properties of the recess 2′ and/or of the nozzle 4 so as to renderone or both of them hydrophobic or hydrophilic (according to the need),as well as other functions. Consequently, in general, the protectivelayer 9 has the function of modifying the surface properties of thefluid-ejection element 1′ (namely, it is a surface-modification layer).

According to the embodiment of FIG. 1 b, the nozzle 4 is provided in theform of a hole that extends completely through the plate 2, but, unlikethe embodiment of FIG. 1 a, the nozzle 4 of FIG. 1 b does not extendinside the recess 2′.

The plate 2 comprises, in this case, a trench 2″ (in what followsreferred to as “recess”, for consistency with the terms adopted indescribing the embodiment of FIG. 1 a) that surrounds completely, orpartially, the nozzle 4; the recess 2″ is separated from the outletsection 4 b of the nozzle 4 by a portion 5′ of the plate 2. Hence, theoutlet section 4 b of the nozzle 4 extends on the first side 2 a of theplate 2. The recess 2″ is delimited perimetrally by walls 3″.

In other words, the recess 2″ extends in the plate 2 defining a closedpolygonal, or circular, or oval path. In turn, the closed polygonal pathdefines the portion 5′ of the plate 2 internal to the closed polygonalpath and, consequently, a portion 5″ of the plate 2 external to theclosed polygonal path. The outlet section 4 b of the nozzle 4 is formedin an area corresponding to the portion 5′ of the plate 2 internal tothe closed polygonal path.

In a way similar to what has been described with reference to FIG. 1 a,the nozzle 4 forms a passage for the fluid contained in the reservoir 6towards the outside of the fluid-ejection element 1″. The inlet section4 a of the nozzle 4 is fluidically coupled directly with the ejectionchannel 8. The distance D_(M), in the direction Z, between the inletsection 4 a and the outlet section 4 b corresponds to the thickness ofthe plate 2 (distance, along Z, between the first and second sides 2 a,2 b). According to one embodiment of the present disclosure, asillustrated more fully in what follows, said distance D_(M) furthercomprises the thickness of the protective layer 9.

The outlet section 4 b of the nozzle 4 has, in top plan view (i.e.,observing the nozzle 4 in the direction Z) a substantially circularshape with diameter d₁. The inlet section 4 a has also, in top planview, a substantially circular shape, but with a diameter d₂ greaterthan d₁.

As has been said, the recess 2″ extends at a distance from the nozzle 4,for example at a distance D_(H), measured starting from the edge of theoutlet section 4 b of the nozzle 4 up to interception of a pointbelonging to the walls 3″ that is closest to the edge of the outletsection 4 b of the nozzle 4.

The distance D_(H) is, for example, between approximately 0.5 μm andapproximately 5 μm. The recess 2″ extends in the structural layer 16 fora depth, measured starting from the first side 2 a of the structurallayer 2, between 0.1 μm and 10 μm, for example, equal to 1 μm.

The presence of the recess 2″ that extends at the distance D_(H) fromthe nozzle 4 prevents any debris, for example deriving from the processof ejection of the fluid from the nozzle 4, and/or undesirable materialwith which the plate 2 might come into contact in use, from possiblyaccumulating in the proximity of the nozzle 4, thus interfering withejection of the fluid from the nozzle 4.

In particular, any possible debris or undesirable material may beremoved, during use, by means of a simple step of cleaning of thesurface of the plate 2. Alternatively, it is the ejection of fluiditself that enables displacement of any possible debris to one side ofthe nozzle 4. By forming the recess 2″ in the proximity of the nozzle 4and alongside it, said debris can accumulate, by displacingspontaneously (as a result of the use of the ejection element 1″) orfollowing upon the cleaning step, within the recess 2″. Consequently,said debris does not remain either on the first side 2 a of the plate 2or in the proximity of the outlet section 4 b of the nozzle 4.

In a way similar to what has already been described with reference toFIG. 1 a, according to one embodiment of the present disclosure, alsothe nozzle plate 2 of FIG. 2 b further comprises a protective layer 9,which extends in such a way as to cover the walls of the hole thatprovides the nozzle 4 (i.e., the walls that connect the inlet section 4a with the outlet section 4 b). Since, according to the embodiment ofFIG. 2 b, the recess is formed at a distance from the outlet section 4 bof the nozzle 4, the protective layer 9 extends on the first side 2 a ofthe plate 2 in such a way as to surround the outlet section 4 b of thenozzle 4, but does not extend within the recess 2″.

The protective layer 9 is made of a material that does not undergo asignificant degradation when it is set in (even prolonged) contact withthe fluid that is to be ejected through the nozzle 4. In this way, evenin the case of ejection of corrosive fluids, the nozzle does not undergoa degradation such as to jeopardize an effective use thereof for theapplication considered.

According to a further embodiment, the protective layer 9 extends alsowithin the recess 2″, improving the resistance to corrosion of the sidewalls 3″ and of the bottom surface of the recess 2″.

The choice of the material used for the protective layer 9 depends uponthe type of use envisaged for the fluid-ejection element 1″. Forexample, in the case where the fluid to be ejected is ink, materialsthat can be used for the protective layer 9 are, for example, siliconcarbide, alumina, hafnium oxide, titanium, tantalum, tungsten, and/oralloys thereof.

In general, the protective layer 9 can have also the function ofimproving the resistance in regard to the operations of cleaning of thefluid-ejection element 1″, improving the sturdiness thereof, modifyingthe properties of the recess 2″ and/or of the nozzle 4 so as to renderone or both of them hydrophobic or hydrophilic (according to the need),as well as other functions. Consequently, in general, the protectivelayer 9 has the function of modifying the surface properties of thefluid-ejection element 1″(namely, it is a surface-modification layer).

FIGS. 2-12 show steps for manufacturing the fluid-ejection element 1′ ofFIG. 1 a.

In particular, steps of production of the nozzle plate 2 and itscoupling with the channel 8 are described. The steps of production ofthe reservoir 6 and its coupling with the ejection channel 8 do not formthe subject of the present disclosure and are consequently not describedin detail in what follows.

The view of the fluid-ejection element 1′ of FIGS. 2-12 corresponds tothe fluid-ejection element 1′ of FIG. 1 a when viewed parallel to thedirection Y, orthogonal to the plane XZ.

With reference to FIG. 2, according to one aspect of the presentdisclosure, a wafer 10 is provided, comprising a substrate 11 made ofsemiconductor material, for example silicon, having a substantiallyuniform thickness, comprised in the range from approximately 200 μm toapproximately 800 μm, for example approximately 400 μm. The substrate 11has a top face 11 a and a bottom face 11 b, opposite to one another inthe direction of the axis Z.

An intermediate layer 12 is formed on the substrate 11 for protectingthe substrate 11 during subsequent manufacturing steps. For example, theintermediate layer 12 is made of silicon oxide (SiO₂) and is formed, forinstance, by means of thermal growth of SiO₂ on the substrate 11 whenthe latter is made of silicon. The intermediate layer 12 is formed bothon the top face 11 a and on the bottom face 11 b of the substrate 11.

According to a different embodiment of the present disclosure, theintermediate layer 12 is formed only on the top face 11 a of thesubstrate 11.

In any case, it is evident that the intermediate layer 12 can be formedby means of a technique different from thermal growth, for example bydeposition of material such as silicon oxide or silicon nitride (SiN),or again some other material.

Irrespective of the technique used for forming the intermediate layer12, the latter has a substantially uniform thickness, comprised in therange from approximately 0.5 μm to approximately 2 μm, for exampleapproximately 1 μm.

As shown in FIG. 3, a sacrificial layer 14 is formed on the top face 11a of the substrate 11, for example by means of a deposition technique.The sacrificial layer 14 may be made either of a material that can beetched away together with the material of which the intermediate layer12 is formed (i.e., by means of one and the same chemical etch) or of amaterial that can be etched selectively with respect to the material ofwhich the intermediate layer 12 is formed. For example, the sacrificiallayer 14 is made of silicon oxide or silicon nitride, or some othermaterial. The sacrificial layer 14 has a thickness comprised in therange from approximately 0.1 μm to approximately 10 μm, for exampleapproximately 1 μm.

In FIG. 4, the sacrificial layer 14 is selectively etched so as toremove the sacrificial layer 14 from the wafer 10 except for regions inwhich it is desired to form the recess 2′ illustrated in FIG. 1 a. Thereis thus formed a sacrificial island 14′ that extends on top of theintermediate layer 12 and of the top face 11 a of the substrate 11.

As shown in FIG. 5, a structural layer 16 is grown on the wafer 10 (onthe top face 11 a of the substrate 11, of the intermediate layer 12, andof the sacrificial island 14′), for example by means of epitaxial growthof silicon. The structural layer 16 has a substantially uniformthickness, comprised in the range from approximately 5 μm toapproximately 100 μm, and preferably from approximately 10 μm to 50 μm,for example 20 μm. According to one embodiment of the presentdisclosure, the structural layer 16 is initially formed with a thicknesslarger than the desired thickness. This is followed by a planarizationstep so as to reach a desired thickness (uniform on the wafer 10) and atthe same time reduce the surface roughness of the structural layer 16.The planarization step is carried out, for example, with the CMP(Chemical Mechanical Planarization) technique.

As shown in FIG. 6 a, the structural layer 16 is etched in such a way asto define an opening 18 in a position corresponding to the sacrificialisland 14′. The opening 18 concurs in forming, in subsequentmanufacturing steps, the nozzle 4. As illustrated in FIG. 6 b, theopening 18 has an extension, in top view, smaller than the extension ofthe sacrificial island 14′ (i.e., the opening 18 is completely containedwithin the sacrificial island 14′).

Etching of the structural layer 16 to form the opening 18 is performed,for example, using the RIE (Reactive Ion Etching) technique, andproceeds until the sacrificial island 14′ is reached, which operates, inthis case, as etch-stop element.

It is evident that, according to different embodiments of the presentdisclosure, the opening 18 can be formed using other wet or dry etchingtechniques.

Irrespective of the technique with which the opening 18 is formed, thelatter has, according to the view of FIG. 6 b, a substantially circularshape. In perspective view (not illustrated), the opening 18 has,according to one aspect of the present disclosure, a substantiallycylindrical shape. The circular base of the opening 18 has a diameterchosen according to the need, in such a way that it is contained insidethe sacrificial island 14′. For example, the diameter is between 1 μmand 40 μm, more in particular between 5 μm and 25 μm. As described morefully in what follows, on account of subsequent manufacturing steps, thediameter of the opening 18 (measured during the step of FIG. 5) islarger than the diameter of the nozzle 4 at the end of the manufacturingsteps.

Once again with reference to FIGS. 6 a and 6 b, a narrowing layer 20 isformed on top of the structural layer 16 and within the opening 18. Thenarrowing layer 20 has a thickness between approximately 1 μm andapproximately 5 μm, for example 2 μm, and is made of a material that canbe etched selectively with respect to the material of which thesacrificial island 14′ is formed. For example, in the case where thesacrificial island 14′ is made of silicon oxide, the narrowing layer 20is made of silicon nitride. Instead, in the case where the sacrificialisland 14′ is made of silicon nitride, the narrowing layer 20 is made ofsilicon oxide. Other materials can, however, be used.

The narrowing layer 20 extends, in particular, at an inner surface 18′that delimits the opening 18 laterally. Preferably, the thicknesspreviously indicated for the narrowing layer 20 is measured on the innersurface 18′ of the opening 18.

As shown in FIG. 7, the narrowing layer 20 is etched by means ofdirective (anisotropic) dry etching, represented in FIG. 7 by the arrows21. In this way, portions of the narrowing layer 20 that extendorthogonal to the etching direction (i.e., portions of the narrowinglayer 20 that extend parallel to the plane XY) are removed faster thanportions of the narrowing layer 20 that extend parallel to the etchingdirection. Consequently, portions of the narrowing layer 20 that extendon top of the structural layer 16 and on top of part of the sacrificialisland 14′ are removed completely; instead, a portion of the narrowinglayer 20 that extends along the lateral surface (inner surface) 18′ ofthe opening 18 is not completely removed, but is shaped in such a way asto assume an at least partially tapered shape, i.e., having anon-uniform thickness D_(SPACER) (measured starting from the innersurface 18′). In particular, the thickness D_(SPACER) decreases movingaway from the sacrificial island 14′ in the direction Z. There is thusformed a narrowing element 20′ extending in the opening 18 in a positioncorresponding, and adjacent, to the inner surface 18′ of the opening 18itself.

As may be noted from FIG. 7, the step of etching the narrowing layer 20enables shaping, during the etching step itself, of the narrowingelement 20′ in the desired way, as described previously. The opening 18thus assumes a shape that resembles, according to one embodiment, atruncated cone. In general, the narrowing element 20′ is configured toshape the opening 18 in such a way that it has a cross section (parallelto the plane XY and extending in a region corresponding to thesacrificial island 14′) having a diameter smaller than the diameter ofthe cross section of the opening 18 (also this considered parallel tothe plane XY) extending in a region corresponding to the exposed surfaceof the structural layer 16. In general, the area of the cross section ofthe opening 18 extending in a region corresponding to the sacrificialisland 14′ is smaller than the area of the cross section extending in aregion corresponding to the exposed surface of the structural layer 16.In use, at the end of the manufacturing steps, the cross section ofsmaller area forms the outlet section of the nozzle 4, whilst the crosssection of larger area forms the inlet section of the nozzle 4.

Said narrowing element 20′ has the function of forming a nozzle 4 havinga tapered shape, as already illustrated in FIG. 1 a. In particular,according to the type of etch that is used for removing the narrowinglayer 20 and the duration of the etch itself, the narrowing element 20′can assume a triangular shape (in cross-sectional view) or else a shape(in cross-sectional view) given by the union of a triangular portion anda quadrangular portion, where the quadrangular portion extends as aprolongation of the triangular portion. In perspective view, this shaperesembles the superposition of a frustoconical portion on a cylindricalportion. Obviously, given that the narrowing element 20′ is monolithicand made of one and the same material, the two portions extend one afteranother with continuity, and without a clear separation. It is evidentthat this description of the narrowing element 20′ is qualitative.Irregularities with respect to the ideal geometrical shape described,due to the manufacturing process, are possible.

As shown in FIG. 8, the sacrificial island 14′ is removed by means ofwet etching. During this etching step, also the portion of theintermediate layer 12 that extends underneath the sacrificial island 14′as far as the substrate 11 is removed. A cavity 24 is thus formed, whichextends underneath the narrowing element 20′ and partially underneaththe structural layer 16. In other words, the cavity 24 extends betweenthe substrate 11 and the narrowing element 20′, and between thesubstrate 11 and part of the structural layer 16.

In the case where the sacrificial island 14′ and the intermediate layer12 are made of materials that cannot be removed with one and the samechemical etch, two subsequent etches are necessary, for removing thesacrificial island 14′ and the portion of intermediate layer 12 lyingunderneath the latter.

As shown in FIG. 9, the protective layer 9 is formed, which extends onthe structural layer 16 and of the narrowing element 20′ and on thewalls that delimit the cavity 24. In particular, the protective layer 9extends on the bottom of the cavity 24 (corresponding to the top face 11a of the substrate 11 exposed during the steps of FIG. 8) and on theportions of the structural layer 16 and of the narrowing element 20′directly facing the cavity 24.

According to one embodiment of the present disclosure, the protectivelayer 9 is deposited using the atomic layer deposition (ALD) technique,depositing a material chosen from among silicon carbide, alumina,hafnium oxide, titanium, tantalum, tungsten, and/or alloys thereof.

The protective layer 9 deposited with the ALD technique (the so-called“conformal film”) has a controlled thickness over the entire surface ofthe nozzle 4. The ALD technique enables formation of the protectivelayer 9 also within the cavity 24, on the surface 11 a of the substrate11, the structural layer 16, and the narrowing element 20′.

The present applicant has found that, with the ALD technique, a goodcovering of all the walls of the cavity 24 that is formed following uponremoval of the sacrificial island 14′ is obtained, also in remoteportions of the latter.

According to one embodiment, the protective layer 9 is deposited withthe etch-assisted HDP technique, which enables a deposited protectivelayer to be obtained characterized by rounded corners.

Other CVD techniques can, however, be used. However, CVD techniquesdifferent from the ALD technique might not guarantee an optimal coveringof the walls of the cavity 24 in remote portions thereof.

As shown in FIG. 10, a grinding step, in a region corresponding to thebottom face 11 b of the substrate 11, enables complete removal of theintermediate layer 12 that extends on the bottom face 11 b of thesubstrate 11, of the substrate 11, and of the portion of protectivelayer 9 formed on the top face 11 a of the substrate 11, so as to reachthe structural layer 16. The plate 2 is thus formed comprising a nozzle4, as described with reference to FIG. 1 a. The plate 2 has a first side2 a covered by the protective layer 9 and a second side 2 b that has therecess 2′ and the nozzle 4.

FIG. 11 a shows, in top view, when viewed from the second side 2 b, thenozzle 4. As may be seen, the nozzle 4 has, in top view and in an areacorresponding to the recess 2′, a substantially circular shape and has adiameter having a first value d₁. The portion of the nozzle 4 in theregion of the recess 2′ is the section of the nozzle 4 from which thereoccurs, in use, ejection of the fluid.

It is evident that, according to further embodiments (not illustrated),the nozzle 4 can have, in top view and in an area corresponding to therecess 2′, an elliptical, quadrangular, polygonal shape, or an irregularshape, or any other shape deemed advantageous for the applicationenvisaged for the nozzle 4.

FIG. 11 b shows, in top view when viewed from the first side 2 a, thenozzle 4. Also in a region corresponding to the first side 2 a, thenozzle 4 has a substantially circular shape, but in this case has adiameter having a second value d₂ larger than the first value d₁. Theportion of the nozzle 4, in the region of the first side 2 a, is thecross section of the nozzle 4 directly facing the ejection channel 8,from which the fluid to be ejected is supplied.

Hence, to return to the cross-sectional view of FIG. 10, the nozzle 4has a tapered region configured to operate as join between the ejectionchannel 8 and the outlet section of the nozzle 4. The cross section ofthe tapered region having a larger diameter d₂ is configured to facedirectly the ejection channel 8, fluidically coupled to the latter.

The ejection channel 8 is formed starting from a substrate 30 made ofsemiconductor material, for example silicon, processed usingmicromachining techniques of a known type (lithography and etching) insuch a way as to form a substantially cylindrical channel 31 having adiameter d_(C) of a base section larger than the diameter d₂ (andconsequently also than the diameter d₁) of the nozzle 4.

With reference to FIG. 12, the substrate 30 is coupled to the first side2 a of the plate 2 according to the known art, for example viawafer-to-wafer bonding, or by means of glue, or with a biadhesive layer,or in some other way. Coupling of the substrate 30 with the plate 2 isperformed in such a way that the straight line, parallel to the axis Z,passing through the center of the nozzle 4, coincides with the straightline, parallel to the axis Z, passing through the center of the ejectionchannel 8.

According to one embodiment of the present disclosure, to facilitate thegrinding operation described with reference to step 10, the step ofcoupling the substrate 30 to the plate 2 is carried out prior to thestep of grinding the substrate 11. In this way, during the grindingoperation, the substrate 30 has the function of reinforcing the plate 2and facilitating handling thereof.

FIGS. 13-19 show steps for manufacturing a fluid-ejection element 100according to a further embodiment of the present disclosure.

With reference to FIG. 13, provided in a way similar to what has alreadybeen described with reference to FIG. 2 for the respective embodiment,is a wafer 100, comprising a substrate 110 made of semiconductormaterial, for example silicon, having a substantially uniform thickness,comprised in the range from approximately 200 μm to approximately 800μm, for example approximately 400 μm. The substrate 110 has a top face110 a and a bottom face 110 b, opposite to one another in the directionof the axis Z.

Formed on the substrate 110 is an intermediate layer 112 for protectingthe substrate 110 during subsequent manufacturing steps. For example,the intermediate layer 112 is made of silicon oxide (SiO₂) and is formedby thermal growth of SiO₂ on the silicon substrate 110. The intermediatelayer 112 is, in particular, formed both on the top face 110 a and onthe bottom face 110 b of the substrate 110. It is evident that theintermediate layer 112 may be formed only on the top face 110 a of thesubstrate 110.

In any case, it is evident that the intermediate layer 112 can be formedusing a technique different from thermal growth, for example bydeposition. Furthermore, the intermediate layer 112 may be made of amaterial other than SiO₂, for example silicon nitride (SiN), or someother material.

Irrespective of the technique used for forming the intermediate layer112, the latter has a substantially uniform thickness, comprised in therange from approximately 0.1 μm to approximately 10 μm, for exampleapproximately 1 μm.

As shown in FIG. 14, on the top face 111 a of the substrate 111 and ofthe intermediate layer 112 a structural layer 116 is formed, for exampleby epitaxial growth of silicon. The structural layer 116 hassubstantially uniform thickness, comprised in the range fromapproximately 5 μm to approximately 100 μm, and preferably fromapproximately 10 μm to 50 μm, for example 20 μm. The structural layer116 is etched in such a way as to define an opening 118 that extendscompletely through the structural layer 116 as far as the intermediatelayer 112.

The location on the wafer 100 and the shape of the opening 118correspond to the ones already described with reference to FIGS. 6 a and6 b of the respective embodiment. In this case, however, the sacrificialisland 14′ is not present.

As shown in FIG. 15, formed on top of the structural layer 116 andwithin the opening 118 is a narrowing layer (or spacer) 120. Thenarrowing layer 120 has a thickness between approximately 1 μm andapproximately 5 μm, for example 2 μm, and is made of a material that canbe etched selectively with respect to the material of which theintermediate layer 112 is formed. For example, in the case where theintermediate layer 112 is made of silicon oxide, the narrowing layer 120is made of silicon nitride. Instead, in the case where the intermediatelayer 112 is made of silicon nitride, the narrowing layer 120 is made ofsilicon oxide. Other materials can, however, be used.

The narrowing layer 120 extends, in particular, on the inner surface118′ that delimits the opening 118 laterally. Preferably, the thicknesspreviously indicated for the narrowing layer 120 is measured in an areacorresponding to the inner surface 118′ of the opening 118.

As shown in FIG. 16, the narrowing layer 120 is etched by directive(anisotropic) dry etching, indicated by the arrows 121 in FIG. 16. Inthis way, portions of the narrowing layer 120 that extend orthogonal tothe etching direction (i.e., portions of the narrowing layer 120 thatextend parallel to the plane XY) are removed faster than portions of thenarrowing layer 120 that extend parallel to the etching direction.Consequently, portions of the narrowing layer 120 extending over thestructural layer 116 and the intermediate layer 112 are removedcompletely; instead, portions of the narrowing layer 120 extending alonglateral surfaces 118′ of the opening 118 are not substantially etched.There is thus formed a narrowing element 120′ extending in the opening118 on the lateral surfaces 118′ thereof. As may be noted from FIG. 16(and as already described with reference to FIG. 7), the step of etchingthe narrowing layer 120 shapes the narrowing element 120′, in particularat their top ends where the opening 118 assumes a substantiallyfrustoconical shape.

As shown in FIG. 17, an etching step is performed for removing theportion of the intermediate layer 112 exposed through the opening 118.In particular, this etching step proceeds until also a portion of theintermediate layer 112 that extends between the intermediate layer 112and the structural layer 116 is removed. In this way, the narrowingelement 120′ and part of the structural layer 116 are partiallysuspended over the substrate 111.

Etching of the intermediate layer 112 according to the step of FIG. 17is an etching of an isotropic type (wet etching or dry etching).

According to a further embodiment, the narrowing element 120′ is made ofthe same material of which the intermediate layer 112 is formed (forexample, silicon oxide). In this case, the etching step according toFIG. 17 removes also part of the narrowing element 120′. However, byforming narrowing elements or spacers 120′ of appropriate thickness, itis possible to overcome this problem.

As shown in FIG. 18, a protective layer 109 is formed, that extend ontop of the structural layer 116 and of the narrowing element 120′. Inparticular, the protective layer 109 extends also over the top face 111a of the substrate 111 exposed during the step of FIG. 17, and on theportions of the structural layer 116 and of the narrowing element 120′facing the top face 111 a of the substrate 111.

The protective layer 109 is similar to the protective layer 9 alreadydescribed with reference to FIGS. 1 a and 9 and is formed in the sameway.

As shown in FIG. 19, a grinding step on the bottom face 111 b of thesubstrate 111 enables a complete removal of the intermediate layer 112that extends on the bottom face 111 b of the substrate 111, of thesubstrate 111, and of the portion of protective layer 109 extendingdirectly in contact with the top face 111 a of the substrate 111. Bystopping the grinding step in this stage, there remains a portion of theintermediate layer 112 surrounding the nozzle 104 such as to form arecess 112′ in the intermediate layer 112. The recess 112′ has, in use,the same function as the recess 2′ of FIG. 1 a.

Alternatively, it is possible to stop the grinding operation at the endof removal of the portion of the protective layer 109 extending directlyon the top face 11 a of the substrate 11, and remove the remainingintermediate layer 112 by means of a selective etching step, for examplea wet etch. A step of dry etching of the protective layer 109 isperformed so as to remove the protective layer 109 around the nozzle 104only partially in order to form a recess similar to the recess 2′ ofFIG. 1 a.

Irrespective of the embodiment, a plate 102 is formed comprising anozzle 104 that is similar to the plate 2 comprising the nozzle 4described with reference to FIG. 1 a and illustrated in said figure. Theplate 102 has a first side 102 a covered with the protective layer 109and a second side 102 b that has the recess 112′.

The plate 102 is coupled to a substrate 130 similar to the substrate 30described with reference to FIG. 12 so as to couple the nozzle 104fluidically to an ejection channel.

FIGS. 20-27 show steps for manufacturing the fluid-ejection element 1″of FIG. 1 b.

In particular, steps for manufacturing the nozzle plate 2 and for itscoupling with the channel 8 are now described. The steps for obtainingthe reservoir 6 and for its coupling with the ejection channel 8 do notform the subject of the present disclosure and are consequently notdescribed in detail in what follows.

The view of the fluid-ejection element 1″ of FIGS. 20-27 corresponds tothe fluid-ejection element 1″ of FIG. 1 b when observed parallel to thedirection Y, in a direction orthogonal to the plane XZ.

With reference to FIG. 20, according to one aspect of the presentdisclosure, a wafer 150 is provided, comprising a substrate 151 made ofsemiconductor material, for example silicon, having a substantiallyuniform thickness, ranging from approximately 200 μm to approximately800 μm, for example of approximately 400 μm. The substrate 151 has a topface 151 a and a bottom face 151 b, opposite to one another in thedirection of the axis Z.

Formed on the substrate 151 is an intermediate layer 152 for protectionof the substrate 151 during subsequent manufacturing steps. For example,the intermediate layer 152 is made of silicon oxide (SiO₂) and isformed, for example, by thermal growth of SiO₂ on the substrate 151 whenthe latter is made of silicon. The intermediate layer 152 is, inparticular, formed both on the top face 151 a and on the bottom face 151b of the substrate 151.

According to a different embodiment of the present disclosure, theintermediate layer 152 is formed only at the top face 151 a of thesubstrate 151.

In any case, it is evident that the intermediate layer 152 may be formedusing a technique other than thermal growth, for example by depositionof material such as silicon oxide or silicon nitride (SiN), or someother material still.

Irrespective of the technique used to form the intermediate layer 152,the latter has a substantially uniform thickness, ranging fromapproximately 0.5 μm to approximately 2 μm, for example of approximately1 μm.

As shown in FIG. 21, formed on the top face 151 a of the substrate 151is a sacrificial layer 154, for example using the deposition technique.The sacrificial layer 154 may be either a material that can be etchedtogether with the material of the intermediate layer 152 (i.e., usingone and the same chemical etch) or a material that can be etchedselectively with respect to the material of the intermediate layer 152.For example, the sacrificial layer 154 is made of silicon oxide orsilicon nitride, or of some other material still. The sacrificial layer154 has a thickness ranging from approximately 0.1 μm to approximately10 μm, for example of approximately 1 μm.

In FIG. 22 a, the sacrificial layer 154 is selectively etched so as toremove the sacrificial layer 154 from the wafer 150 except for regionsin which the recess 2″ shown in FIG. 1 b is to be formed. A sacrificialregion 154′ is thus formed, which extends over the intermediate layer152 and the top face 151 a of the substrate 151. The sacrificial region154′ has, in the top plan view of FIG. 22 b, a polygonal shape, andforms a frame that surrounds the region of the wafer 150 in which, insubsequent manufacturing steps, the nozzle 4 will be formed.

As shown in FIG. 23, a structural layer 156 is grown on the wafer 150(on the top face 151 a of the substrate 151, on the intermediate layer152, and on the sacrificial region 154′), for example by epitaxialgrowth of silicon. The structural layer 156 has a substantially uniformthickness, ranging from approximately 5 μm to approximately 100 μm, andpreferably from approximately 10 μm to 50 μm, for example of 20 μm.According to one embodiment of the present disclosure, the structurallayer 156 is initially formed with a thickness greater than the desiredthickness. A planarization step is carried out so as to reach a desiredthickness (which is uniform on the wafer 150) and at the same timereduce the surface roughness of the structural layer 156. Theplanarization step is carried out, for example, with the CMP (ChemicalMechanical Planarization) technique.

As shown in FIGS. 24 a and 24 b, the structural layer 156 is etched insuch a way as to define an opening 158 surrounded by the sacrificialregion 154′. The opening 158 concurs in forming the nozzle 4, insubsequent manufacturing steps. FIG. 24 a is a cross-sectional view ofFIG. 24 b, taken along the line of cross section XXIV-XXIV of FIG. 24 b.

Etching of the structural layer 156 to form the opening 158 is carriedout, for example, with the RIE (Reactive Ion Etching) technique, andproceeds for the entire thickness of the structural layer 156.

It is evident that, according to different embodiments of the presentdisclosure, the opening 158 can be formed using other wet-etching ordry-etching techniques.

Irrespective of the technique with which the opening 158 is formed, thelatter has, according to the view of FIG. 24 b, a substantially circularshape. In perspective view (not illustrated), the opening 158 has,according to one aspect of the present disclosure, a substantiallycylindrical shape. The circular base of the opening 158 has a diameterchosen according to the need, in such a way that it is contained insidethe sacrificial island 154′. For example, the diameter is between 1 μmand 40 μm, more in particular between 5 μm and 25 μm. As described morefully in what follows, on account of subsequent manufacturing steps, thediameter of the opening 158 in this process step is larger than thediameter of the nozzle 4 at the end of the manufacturing steps heredescribed.

Once again with reference to FIGS. 24 a and 24 b, a narrowing layer 160is formed on top of the structural layer 156 and within the opening 158.The narrowing layer 160 has a thickness between approximately 1 μm andapproximately 5 μm, for example 2 μm, and is made, for example, ofsilicon oxide or silicon nitride. Other materials may, however, be used.

The narrowing layer 160 extends, in particular, at an inner surface 158′that delimits the opening 158 laterally. Preferably, the thicknesspreviously indicated for the narrowing layer 160 is measured on theinner surface 158′ of the opening 158.

As shown in FIG. 25, the narrowing layer 160 is etched by means ofdirective (anisotropic) dry etching. In this way, portions of thenarrowing layer 160 that extend orthogonal to the etching direction(i.e., portions of the narrowing layer 160 that extend parallel to theplane XY) are removed faster than portions of the narrowing layer 160that extend parallel to the etching direction. Consequently, portions ofthe narrowing layer 160 that extend on top of the structural layer 156and on top of the intermediate layer 152 are removed completely;instead, a portion of the narrowing layer 160 that extends along thelateral surface (inner surface) 158′ of the opening 158 is notcompletely removed, but is shaped in such a way as to assume an at leastpartially tapered shape, i.e., having a non-uniform thickness D_(SPACER)(measured starting from the inner surface 158′). In particular, thethickness D_(SPACER) decreases moving away from the intermediate layer152 in the direction Z. There is thus formed a narrowing element 160′extending in the opening 158 in a position corresponding, and adjacent,to the inner surface 158′ of the opening 158 itself.

As may be noted from FIG. 25, the step of etching the narrowing layer160 enables shaping, during the etching step itself, of the narrowingelement 160′ in the desired way, as described previously. The opening158 thus assumes a shape that resembles, according to one embodiment, atruncated cone. In general, the narrowing element 160′ is configured toshape the opening 158 in such a way that it has a cross section(parallel to the plane XY and extending in a region corresponding to theintermediate layer 152) having a diameter smaller than the diameter ofthe cross section of the opening 158 (also this considered parallel tothe plane XY) extending in a region corresponding to the exposed surfaceof the structural layer 16. In general, the area of the cross section ofthe opening 158 extending in a region corresponding to the intermediatelayer 152 is smaller than the area of the cross section extending in aregion corresponding to the exposed surface of the structural layer 16.In use, at the end of the manufacturing steps, the cross section ofsmaller area forms the outlet section of the nozzle 4, whilst the crosssection of larger area forms the inlet section of the nozzle 4.

The narrowing element 160′ has the function of forming a nozzle 4 havinga tapered shape, as already illustrated in FIG. 1 b. In particular,according to the type of etch that is used for removing the narrowinglayer 160 and the duration of the etch itself, the narrowing element160′ can assume a triangular shape (in cross-sectional view) or else ashape (in cross-sectional view) given by the union of a triangularportion and a quadrangular portion, where the quadrangular portionextends as a prolongation of the triangular portion. In perspectiveview, this shape resembles the superposition of a frustoconical portionon a cylindrical portion. Obviously, given that the narrowing element160′ is monolithic and made of one and the same material, the twoportions extend one after another with continuity, and without a clearseparation. It is evident that this description of the narrowing element160′ is qualitative. Irregularities with respect to the idealgeometrical shape described, due to the manufacturing process, arepossible.

During the step of FIG. 25 an etch of the intermediate layer 152 exposedthrough the opening 158 is moreover carried out. Said etch isrepresented, in FIG. 25, as an etch configured to remove for the entirethickness (along Z) the portion of the intermediate layer 152 exposedthrough the opening 158.

However, according to a different embodiment, said etch may be partial,i.e., such as to remove only a fraction of the thickness (along Z) ofthe portion of the intermediate layer 152 exposed through the opening158, to form a recess in the intermediate layer 152 (this embodiment isnot shown in the figure).

As shown in FIG. 26, the protective layer 9 is formed on the structurallayer 156, on the narrowing element 160′, and inside the opening 158 (inparticular on the surface portion of the substrate 151 exposed throughthe opening 158, as described with reference to FIG. 25).

In the case where during the step of FIG. 25 just a fraction of thethickness (along Z) of the portion of the intermediate layer 152 exposedthrough the opening 158 is etched, the protective layer 9 extends in therecess of the intermediate layer 152 exposed through the opening 158.

According to an embodiment of the present disclosure, the protectivelayer 9 is deposited by means of the ALD (Atomic-Layer Deposition)technique, by depositing a material chosen from among silicon carbide,alumina, hafnium oxide, titanium, tantalum, tungsten, and/or alloysthereof.

Other CVD techniques may, however, be used.

As shown in FIG. 27, a step of grinding in a region corresponding to thebottom face 151 b of the substrate 151 enables complete removal of theintermediate layer 152 that extends in an area corresponding to thebottom face 151 b of the substrate 151, the substrate 151, and theportion of the protective layer 9 that extends on the substrate 151, soas to reach the structural layer 156.

Also in the case where the protective layer 9 is formed in a recess ofthe intermediate layer 152, the grinding step enables removal thereof.

The surface of the structural layer 156, previously coupled to theintermediate layer 152, is now exposed. It is hence possible to carryout a selective etch for removing the sacrificial region 154′, to form atrench that provides the recess 2″ described with reference to FIG. 1 b.

A subsequent step of deposition of protective material (for example,silicon carbide, alumina, hafnium oxide, titanium, tantalum, tungsten,and/or alloys thereof) at the second face 2 b of the plate 2 enablesextension of the protective layer 9 also as far as the second face 2 b,so as protect it from any possible aggression due to the fluid ejectedby the nozzle 4 during use.

In this way, the plate 2 is formed comprising a nozzle 4 surrounded bythe recess 2″, as described with reference to FIG. 1 b. According tothis embodiment, the plate 2 has a first face 2 a covered by theprotective layer 9 and a second face 2 b that has the recess 2′ and thenozzle 4.

Finally, it is possible to form the ejection channel 8 by coupling asubstrate to the plate 2, in a way similar to what has already beendescribed with reference to FIG. 12, and not described any furtherherein.

It is to be appreciated that various steps of the methods may beperformed sequentially, parallel, omitted or in an order different fromthe order that is illustrated.

FIG. 28 shows a fluid-ejection device 200 comprising a plate 2 or 102provided with a plurality of nozzles 4 or 104 and produced according tothe method of FIGS. 2-12, or according to the method of FIGS. 13-19, oraccording to the method of FIGS. 20-27.

The fluid-ejection device 200 comprises a reservoir 6, set underneaththe plate 2, 102 and configured to contain in an internal housing 202 ofits own a liquid or fluid substance 205 (for example, ink) that, in use,must be made to come out of the nozzles 4; 104 through the ejectionchannels 6. Actuation of the fluid-ejection device 200 can be obtainedin various ways, for example by an actuator 204 of a piezoelectric type,fixed with respect to a bottom face of the reservoir 6 opposite to thenozzle plate 2. Alternatively, a plurality of actuators of apiezoelectric type or thermal ink jet type can be provided (in a way notshown), set in an area corresponding to a respective nozzle 4, 104, forexample immediately underneath the respective nozzle 4, 104, in theejection channel 8.

According to a further embodiment, actuation of the fluid-ejectiondevice 200 is of a continuous type, in which the reservoir 6 is acontinuously pressurized reservoir.

Other modalities of arrangement of the actuators are, however, possible.For example, each nozzle 4, 104 can be fluidically coupled to arespective reservoir, and each reservoir can be provided with arespective actuation element 204. Or again, a set of nozzles 4, 104 isfluidically coupled to one and the same reservoir, and another set ofnozzles is fluidically coupled to a further reservoir. The reservoirscan be filled with fluids different from one another.

With reference to FIG. 28, when activated by means of an appropriatecontrol electronics (not illustrated), the actuator 204 induces avibration that is transmitted through the reservoir 6 to the fluid 205contained in the housing 202, causing exit thereof through the nozzles4, 104.

Provided according to one embodiment is an inlet mouth 206 forrecharging the reservoir 6 with further liquid or fluid substance whenthis, following upon use of the fluid-ejection device 200, is used up.Alternatively, the fluid-ejection device 200 is of a non-rechargeabletype, and the inlet mouth 206 is omitted.

According to one embodiment of the present disclosure, thefluid-ejection device 200 is a printing cartridge, for printers of anink jet type.

FIG. 29 shows schematically an ink jet printer 300 provided with afluid-ejection device 200 (having the function of printing cartridge)which comprises a nozzle plate 2, 102 having a plurality of nozzles 4,104 of the type described according to the present disclosure, andobtained according to the teachings of the present disclosure.

The ink jet printer 300 further comprises a control electronics 310,comprising a control card and/or a microprocessor and/or a memory forgoverning and managing the printing operations. The control electronics310 can further comprise a frequency oscillator operatively coupled tothe actuator 204 for controlling the frequency of oscillation of theactuator 204, in the case where the latter is of a piezoelectric type.

From an examination of the characteristics of the disclosure obtainedaccording to the present disclosure the advantages afforded are evident.

In particular, with the disclosure according to the present disclosureis fully obtained via a manufacturing process compatible withmanufacturing technologies of a MEMS type, starting from a wafer made ofsemiconductor material of a standard type. Moreover, the manufacturingprocess described entails a limited number of processing steps, makingpossible industrial production of items with low cost an high yield.

Furthermore, the respective narrowing elements 20′, 120′, 160′ formed asdescribed previously, are self-aligned, respectively, to the openings18, 118, 158 so that a further step of alignment of the narrowingelements 20′, 120′, 160′ with the hole that defines the nozzle 4 is notrequired.

Finally, it is clear that modifications and variations may be made towhat has been described and illustrated herein, without therebydeparting from the sphere of protection of the present disclosure, asdefined in the annexed claims.

It is evident that the steps of the method described with reference toFIGS. 2-12, 13-19, 20-27 (according to the respective embodiments of thepresent disclosure) can be applied to the production of a plurality ofnozzles housed in one and the same nozzle plate 2.

According to a further embodiment, a recess 2′ (of the same type as theone of FIG. 1 a) can house a plurality of nozzles 4.

According to a further embodiment, a trench recess 2″ (of the same typeas the one of FIG. 1 b) can surround a plurality of nozzles 4.

The various embodiments described above can be combined to providefurther embodiments. These and other changes can be made to theembodiments in light of the above-detailed description. In general, inthe following claims, the terms used should not be construed to limitthe claims to the specific embodiments disclosed in the specificationand the claims, but should be construed to include all possibleembodiments along with the full scope of equivalents to which suchclaims are entitled. Accordingly, the claims are not limited by thedisclosure.

1. A process for manufacturing a nozzle plate for a fluid-ejectiondevice, the method comprising: forming a structural layer over a firstside of a first substrate of semiconductor material, the structurallayer having a respective first side and second side, the second side ofthe structural layer facing the first side of the first substrate;forming a first through hole in the structural layer by removing aportion of the structural layer, said first through hole having an innersurface, an inlet section at the first side of the structural layer, andan outlet section at the second side of the structural layer; forming anarrowing element on the inner surface of the first through hole;tapering the narrowing element so that the inlet section of the firstthrough hole has an area larger than a respective area of the outletsection of the first through hole; and removing the first substrate, theremoving rendering accessible the first through hole.
 2. The processaccording to claim 1, further comprising forming, in a positioncorresponding to the second side of the structural layer, a recessconfigured to at least partially surround the outlet section of thefirst through hole.
 3. The process according to claim 2, wherein saidrecess has a perimeter having a shape that is one of a polygonal,polygonal with rounded corners, circular, oval, circular with roundedcorners, and oval with rounded corners.
 4. The process according toclaim 2, wherein forming the first through hole comprises forming saidoutlet section of the first through hole in said recess.
 5. The processaccording to claim 2, wherein the forming said recess comprises forminga trench path, and forming the first through hole comprises forming saidoutlet section of the first through hole enclosed by said trench path.6. The process according to claim 1, wherein: forming the narrowingelement comprises depositing, in the first through hole, a narrowinglayer; and tapering the narrowing element comprises etching thenarrowing layer in an etching direction that is substantially parallelto the surface of the first through hole.
 7. The process according toclaim 1, further comprising forming a surface-modification layer insidethe first through hole that covers and protects the narrowing element.8. The process according to claim 7, wherein forming thesurface-modification layer comprises depositing, on the narrowingelement, a material that includes at least one of silicon carbide,alumina, hafnium oxide, titanium, tantalum, tungsten, and alloysthereof.
 9. The process according to claim 7, wherein forming thesurface-modification layer comprises forming the surface-modificationlayer on portions of the narrowing element and of the structural layerfacing the first substrate.
 10. The process according to claim 1,further comprising: forming an intermediate layer over the first side ofthe first substrate; wherein forming the structural layer comprisesforming said structural layer over the intermediate layer; and whereinforming the recess comprises: etching the intermediate layer in a regioncorresponding to the inlet section of said first through hole; andremoving a portion of the intermediate layer extending between thenarrowing element and the first substrate, and between a portion of thestructural layer adjacent to the narrowing element and the firstsubstrate by further etching the intermediate layer.
 11. The processaccording to claim 1, further comprising: forming an intermediate layerover the first side of the first substrate; and forming a sacrificialisland on the intermediate layer; and wherein: forming the structurallayer comprises forming said structural layer on the intermediate layerand over the sacrificial island; forming the first through holecomprises forming said first through hole on the sacrificial island, andin such a way that the first through hole is contained by thesacrificial island; and forming the recess comprises forming a cavityextending partially between the first substrate and the structurallayer, and between the first substrate and the narrowing element byselectively etching the sacrificial island and a portion of theintermediate layer extending underneath the sacrificial island.
 12. Theprocess according to claim 11 further comprising forming asurface-modification layer inside the first through hole that covers andprotects the narrowing element, and wherein forming thesurface-modification layer comprises forming the surface-modificationlayer in surface portions of the narrowing element and of the structurallayer facing said cavity.
 13. The process according to claim 1, furthercomprising: forming a recess in the second side of the structural thatat least partially surrounds the outlet section of the first throughhole; forming an intermediate layer over the first face of the firstsubstrate; and forming a sacrificial island, defining a parameter ofsaid recess, on the intermediate layer, the sacrificial island defininga region of the intermediate layer internal to said path and a region ofthe intermediate layer external to said path; and wherein: forming thestructural layer comprises forming said structural layer over theintermediate layer and on the sacrificial island; forming the firstthrough hole comprises forming said first through hole in the region ofthe intermediate layer internal to said path; and wherein forming therecess comprises: selectively removing the first substrate and theintermediate layer; and selectively etching the sacrificial island. 14.The process according to claim 1, further comprising: providing a secondsubstrate made of semiconductor material; forming a second through holethrough said second substrate by etching said second substrate; andcoupling the second substrate to the structural layer in such a way thatthe second through hole is aligned with the first through hole.
 15. Anozzle plate for a fluid-ejection device, the nozzle plate comprising: astructural layer having a first side and a second side; a first throughhole having an inner surface extending through the structural layer,said first through hole having an inlet section at the first side of thestructural layer and an outlet section at the second side of thestructural layer; and a narrowing element adjacent to the inner surfaceof the first through hole, and including a tapered portion such that theinlet section of the first through hole has an area larger than arespective area of the outlet section of the first through hole, saidthrough hole and said narrowing element forming an ejection nozzle ofsaid nozzle plate.
 16. The nozzle plate according to claim 15, furthercomprising a recess extending in the structural layer and at leastpartially surrounding the outlet section of the first through hole. 17.The nozzle plate according to claim 16, wherein said recess has aperimeter having a shape that is one of a polygonal, polygonal withrounded corners, circular, and oval.
 18. The nozzle plate according toclaim 16, wherein the outlet section of the first through hole extendsin the recess.
 19. The nozzle plate according to claim 16, wherein saidrecess comprises a trench, the outlet section of the first through holebeing surrounded by said trench.
 20. The nozzle plate according to claim16, wherein the recess extends in the structural layer to a depth ofapproximately 0.1 μm to approximately 10 μm.
 21. The nozzle plateaccording to claim 16, wherein a wall of said recess extends at aminimum distance from the outlet section of the ejection nozzle betweenapproximately 3 μm and approximately 30 μm.
 22. The nozzle plateaccording to claim 15, further comprising a surface-modification layerthat covers the narrowing element, said surface-modification layercomprising a material resistant to said fluid.
 23. The nozzle plateaccording to claim 22, wherein the surface-modification layer extends inthe recess and covers the structural layer.
 24. The nozzle plateaccording to claim 15, wherein the narrowing element further comprises asubstantially cylindrical portion, extending as a prolongation of saidtapered portion between the tapered portion and the outlet section ofthe first through hole.
 25. The nozzle plate according to claim 15,further comprising a substrate made of semiconductor material providedwith a second through hole, the substrate being coupled to thestructural layer in such a way that the second through hole is alignedto the first through hole.
 26. A fluid-ejection device, comprising: areservoir having an internal chamber configured to contain a fluidsubstance; an actuator connected to the reservoir and configured tocause expulsion of the fluid substance from the reservoir; and a nozzleplate in fluid communication with the reservoir to enable expulsion ofthe fluid substance through the nozzle, the nozzle plate including: astructural layer having a first side and a second side; a through holehaving an inner surface extending through the structural layer, saidthrough hole having an inlet section at the first side of the structurallayer and an outlet section at the second side of the structural layer;and a narrowing element adjacent to the surface of the through hole, andincluding a tapered portion such that the inlet section of the throughhole has an area larger than a respective area of the outlet section ofthe through hole, said through hole and said narrowing element formingan ejection nozzle of said nozzle plate.
 27. A printing machinecomprising the fluid-ejection device according to claim
 26. 28. Thefluid-ejection device according to claim 26, further comprising a recessextending in the structural layer and at least partially surrounding theoutlet section of the through hole.
 29. The fluid-ejection deviceaccording to claim 26, wherein the outlet section of the first throughhole extends in the recess.